Thrombin is a serine protease present in blood plasma in the form of a precursor, prothrombin. Thrombin plays a central role in the mechanism of blood coagulation by converting the solution plasma protein, fibrinogen, into insoluble fibrin.
Edwards et al., J. Amer. Chem. Soc., (1992) vol. 114, pp. 1854-63, describes peptidyl a-ketobenzoxazoles which are reversible inhibitors of the serine proteases human leukocyte elastase and porcine pancreatic elastase.
European Publication 363 284 describes analogs of peptidase substrates in which the nitrogen atom of the scissile amide group of the substrate peptide has been replaced by hydrogen or a substituted carbonyl moiety.
Australian Publication 86245677 also describes peptidase inhibitors having an activated electrophilic ketone moiety such as fluoromethylene ketone or a-keto carboxyl derivatives.
R. J. Brown et al., J. Med. Chem., Vol. 37, pages 1259-1261 (1994) describes orally active, non-peptidic inhibitors of human leukocyte elastase which contain trifluoromethylketone and pyridinone moieties.
H. Mack et al., J. Enzyme Inhibition, Vol. 9, pages 73-86 (1995) describes rigid amidino-phenylalanine thrombin inhibitors which contain a pyridinone moiety as a central core structure.
The invention includes compounds for inhibiting loss of blood platelets, inhibiting formation of blood platelet aggregates, inhibiting formation of fibrin, inhibiting thrombus formation, and inhibiting embolus formation in a mammal, comprising a compound of the invention in a pharmaceutically acceptable carrier. These compounds may optionally include anticoagulants, antiplatelet agents, and thrombolytic agents. The compounds can be added to blood, blood products, or mammalian organs in order to effect the desired inhibitions.
The invention also includes a compound for preventing or treating unstable angina, refractory angina, myocardial infarction, transient ischemic attacks, atrial fibrillation, thrombotic stroke, embolic stroke, deep vein thrombosis, disseminated intravascular coagulation, ocular build up of fibrin, and reocclusion or restenosis of recanalized vessels, in a mammal, comprising a compound of the invention in a pharmaceutically acceptable carrier. These compounds may optionally include anticoagulants, antiplatelet agents, and thrombolytic agents.
The invention also includes a method for reducing the thrombogenicity of a surface in a mammal by attaching to the surface, either covalently or noncovalently, a compound of the invention.
Compounds of the invention are useful as thrombin inhibitors and have therapeutic value in for example, preventing coronary artery disease, and have the following structure: 
wherein
W is selected from the group consisting of
1) hydrogen,
2) a 5- to 7-membered mono- or a 9- to 10-membered fused bicyclic heterocyclic ring having carbon ring atoms and heteroatom ring atoms which ring can be saturated or unsaturated, wherein the ring contains
a) from one to four heteroatoms selected from the group consisting of N, O and S, and wherein the ring is unsubstituted, or
b) from one to four N atoms, and where one or more of the ring atoms are substituted with one or more of
i) C1-4 alkyl,
ii) hydroxy,
iii) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
iv) CONH2,
v) CH2OH,
i) SO2NH2,
vii) halogen,
viii) amino,
ix) aryl,
x) C3-7 cycloalkyl,
xi) CF3,
xii) OCF3 
xiii) N(CH3)2,
xiv) xe2x80x94C1-3alkylaryl,
xv) heterocyclic ring,
xvi) C1-4 alkoxy,
xvii) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
xviii) C1-4 thioalkoxy, or
xix) cyano,
3) a 5- to 7-membered mono- or a 9- to 10-membered fused bicyclic non-heterocyclic saturated ring which is unsubstituted or substituted with one or more of
a) C1-4 alkyl,
b) hydroxy,
c) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
d) CONH2,
e) CH2OH,
f) SO2NH2,
g) halogen,
h) amino,
i) aryl,
j) C3-7 cycloalkyl,
k) CF3,
l) OCF3 
m) N(CH3)2,
n) xe2x80x94C1-3alkylaryl,
o) heterocyclic ring,
p) C1-4 alkoxy,
q) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
r) C1-4thioalkoxy,or
s) cyano,
4) a 6-membered mono or 9- to 10-membered fused bicyclic non-heterocyclic unsaturated ring which is unsubstituted or substituted with one or more of
a) C1-4alkyl,
b) hydroxy,
c) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
d) CONH2,
e) CH2OH,
f) SO2NH2,
g) halogen,
h) amino,
i) aryl,
j) C3-7 cycloalkyl,
k) CF3,
l) OCF3,
m) N(CH3)2,
n) xe2x80x94C1-3alkylaryl,
o) heterocyclic ring,
p) C1-4 alkoxy,
q) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
r) C1-4 thioalkoxy, or
s) cyano,
5) CF3,
6) C3-7 cycloalkyl, unsubstituted, monosubstituted with halogen or aryl, or disubstituted with halogen,
7) C7-12 bicyclic alkyl,
8) C10-16 tricyclic alkyl,
9) 
xe2x80x83where m is 0-3, and each R12 can be the same or different,
10) 
xe2x80x83where p is 1-4,
11) 
xe2x80x83where mis 0-3,
12) 
13) 
xe2x80x83where mis 0 or 1,
14) 
15) 
xe2x80x83wherein m is 0-3, and each R12 can be the same or different, wherein the R12 substituents can together form a ring, with the C to which they are bonded, represented by C3-7 cycloalkyl,
16) 
xe2x80x83wherein q is 0-2, and each R12 can be the same or different, wherein the R12 substituents can together form a ring, with the C to which they are bonded, represented by C3-7 cycloalkyl,
17) 
xe2x80x83wherein r is 0-4, and each R2 can be the same or different, wherein the R2 substituents can together form a ring, with the C to which they are bonded, represented by C3-7 cycloalkyl, C7-12 bicyclic alkyl, C10-16 tricyclic alkyl, or a 5- to 7-membered mono- or 9- to 10-membered fused bicyclic heterocyclic ring, which can be saturated or unsaturated, and which contains from one to three heteroatoms selected from the group consisting of N, O and S,
18) 
xe2x80x83wherein n and p are independently 1-4,
19) 
xe2x80x83wherein each R12 can be the same or different,
20) 
xe2x80x83and
21) 
xe2x80x83wherein t is 1-4 and q is independently 0-2;
R2 is selected from the group consisting of
1) hydrogen,
2) a 5- to 7-membered mono- or a 9- to 10-membered fused bicyclic heterocyclic ring having carbon ring atoms and heteroatom ring atoms which ring can be saturated or unsaturated, wherein the ring contains
a) from one to four heteroatoms selected from the group consisting of N, O and S, and wherein the ring is unsubstituted, or
b) from one to four N atoms, and where one or more of the ring atoms are substituted with one or more of
i) C1-4 alkyl,
ii) hydroxy,
iii) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
iv) CONH2,
v) CH2OH,
vi) SO2NH2,
vii) halogen,
viii) amino,
ix) aryl,
x) C3-7 cycloalkyl,
xi) CF3,
xii) OCF3,
xiii) N(CH3)2,
xiv) xe2x80x94C1-3alkylaryl,
xv) heterocyclic ring,
xvi) C1-4 alkoxy,
xvii) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is
xviii) C1-4thioalkoxy, or
xix) cyano,
3) a 5- to 7-membered mono- or a 9- to 10-membered fused bicyclic non-heterocyclic saturated ring which is unsubstituted or substituted with one or more of
a) C1-4 alkyl,
b) hydroxy,
c) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
d) CONH2,
e) CH2OH,
f) SO2NH2,
g) halogen,
h) amino,
i) aryl,
j) C3-7 cycloalkyl,
k) CF3,
l) OCF3,
m) N(CH3)2,
n) xe2x80x94C1-3alkylaryl,
o) heterocyclic ring,
p) C1-4 alkoxy,
q) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, xis 1,
r) C1-4 thioalkoxy, or
s) cyano,
4) a 6-membered mono or 9- to 10-membered fused bicyclic non-heterocyclic unsaturated ring which is unsubstituted or substituted with one or more of
a) C1-4 alkyl,
b) hydroxy,
c) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
d) CONH2,
e) CH2OH,
f) S02NH2,
g) halogen,
h) amino,
i) aryl,
j) C3-7 cycloalkyl,
k) CF3,
l) OCF3,
m) N(CH3)2,
n) xe2x80x94C1-3alkylaryl,
o) heterocyclic ring,
p) C1-4 alkoxy,
q) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
r) C1-4 thioalkoxy, or
s) cyano,
5) C1-7 alkyl, unsubstituted or substituted with one or more of
a) hydroxy,
b) COOH,
c) halogen,
d) amino,
e) aryl,
f) C3-7 cycloalkyl,
g) CF3,
h) N(CH3)2,
i) xe2x80x94C1-3alkylaryl,
j) heterocyclic ring,
k) C1-4 alkoxy,
l) C1-4 thioalkoxy, or
m) cyano,
6) CF3,
7) C3-7 cycloalkyl, unsubstituted, monosubstituted with halogen or aryl, or disubstituted with halogen,
8) C7-12 bicyclic alkyl, and
9) C10-16 tricyclic alkyl;
R3 and X are independently selected from the group consisting of
1) hydrogen,
2) halogen,
3) cyano,
4) C1-4 alkylthio,
5) C1-4 alkylsulfinyl,
6) C1-4 alkylsulfonyl,
7) C1-4 alkyl,
8) C3-7 cycloalkyl, and
9) trifluoromethyl;
A is 
xe2x80x83wherein Y1 and Y2 are independently selected from the group consisting of
1) hydrogen,
2) C1-4 alkyl,
3) C1-4 alkoxy,
4) FuHvC(CH2)0-1 Oxe2x80x94, wherein u and v are either 1 or 2, provided that when u is 1, v is 2, and when u is 2, v is 1,
5) C3-7 cycloalkyl,
6) C1-4 alkylthio,
7) C1-4 alkylsulfinyl,
8) C1-4 alkylsulfonyl,
9) halogen
10) cyano, and
11) trifluoromethyl, and
xe2x80x83wherein b is 0 or 1; and
R12 is selected from the group consisting of
1) hydrogen,
2) halogen,
3) a 5- to 7-membered mono- or a 9- to 10-membered fused bicyclic heterocyclic ring having carbon ring atoms and heteroatom ring atoms which ring can be saturated or unsaturated, wherein the ring contains
a) from one to four heteroatoms selected from the group consisting of N, O and S, and wherein the ring is unsubstituted, or
b) from one to four N atoms, and where one or more of the ring atoms are substituted with one or more of
i) C1-4 alkyl,
ii) hydroxy,
iii) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
iv) CONH2,
v) CH2OH,
vi) SO2NH2,
vii) halogen,
viii) amino,
ix) aryl,
x) C3-7 cycloalkyl,
xi) CF3,
xii) OCF3,
xiii) N(CH3)2,
xiv) xe2x80x94C1-3alkylaryl,
xv) heterocyclic ring,
xvi) C1-4 alkoxy,
xvii) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
xviii) C1-4 thioalkoxy, and
xix) cyano,
4) a 5- to 7-membered mono- or a 9- to 10-membered fused bicyclic non-heterocyclic saturated ring which is unsubstituted or substituted with one or more of
a) C1-4 alkyl,
b) hydroxy,
c) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
d) CONH2,
e) CH2OH,
f) SO2NH2,
g) halogen,
h) amino,
i) aryl,
j) C3-7 cycloalkyl,
k) CF3,
I) OCF3,
m) N(CH3)2,
n) xe2x80x94C1-3alkylaryl,
o) heterocyclic ring,
p) C1-4 alkoxy,
q) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
r) C1-4 thioalkoxy, or
s) cyano,
5) a 6-membered mono or 9- to 10-membered fused bicyclic non-heterocyclic unsaturated ring which is unsubstituted or substituted with one or more of
a) C1-4 alkyl,
b) hydroxy,
c) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
d) CONH2,
e) CH2OH,
f) SO2NH2,
g) halogen,
h) amino,
i) aryl,
j) C3-7 cycloalkyl,
k) CF3,
l) OCF3,
m) N(CH3)2,
n) xe2x80x94C1-3alkylaryl,
o) heterocyclic ring,
p) C1-4 alkoxy,
q) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
r) C1-4 thioalkoxy, or
s) cyano,
6) biphenyl,
7) CF3,
8) C3-7 cycloalkyl,
9) C7-12 bicyclic alkyl, and
10) C10-16 tricyclic alkyl;
or a pharmaceutically acceptable salt thereof.
In a class of compounds, Y1 and Y2 are independently selected from the group consisting of hydrogen, C1-4 alkyl, halogen, C1-4 alkylthio, C1-4 alkylsulfinyl, C1-4 alkylsulfonyl, and C1-4 alkoxy.
In a subclass of the class of compounds, Y1 and Y2 are independently selected from the group consisting of hydrogen, F, CH3, SCH3, SOCH3, SO2CH3, and OCH3.
In a group of the subclass of compounds, A is selected from the group consisting of 
where b is 0 or 1.
In a subgroup of the group of compounds, X is hydrogen, R3 is CH3, Cl, or CN, and W is R2CF2C(R12)2 or R2CH2C(R12)2.
In a family of the subgroup of compounds, R12 is hydrogen.
In a subfamily of the family of compounds, R2 is selected from the group consisting of
1) a 5- to 7-membered mono- or a 9- to 10-membered fused bicyclic heterocyclic ring having carbon ring atoms and heteroatom ring atoms which ring can be saturated or unsaturated, wherein the ring contains
a) from one to four heteroatoms selected from the group consisting of N, O and S, and wherein the ring is unsubstituted, or
b) from one to four N atoms, and where one or more of the ring atoms are substituted with one or more of
i) C1-4 alkyl,
ii) hydroxy,
iii) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
iv) CONH2,
v) CH2O H,
vi) SO2NH2,
vii) halogen,
viii) amino,
ix) aryl,
x) C3-7 cycloalkyl,
xi) CF3,
xii) OCF3,
xiii) N(CH3)2,
xiv) xe2x80x94C1-3alkylaryl,
xv) heterocyclic ring,
xvi) C1-4 alkoxy,
xvii) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
xviii) C1-4 thioalkoxy, or
xix) cyano, and
2) a 6-membered mono or 9- to 10-membered fused bicyclic non-heterocyclic unsaturated ring which is unsubstituted or substituted with one or more of
a) C1-4 alkyl,
b) hydroxy,
c) COORxe2x80x2, where Rxe2x80x2 is hydrogen or C1-4 alkyl,
d) CONH2,
e) CH2OH,
f) SO2NH2,
g) halogen,
h) amino,
i) aryl,
j) C3-7 cycloalkyl,
k) CF3,
l) OCF3,
m) N(CH3)2,
n) xe2x80x94C1-3alkylaryl,
o) heterocyclic ring,
p) C1-4 alkoxy,
q) FwHxC(CH2)0-1 Oxe2x80x94, wherein w and x are either 1 or 2, provided that when w is 1, x is 2, and when w is 2, x is 1,
r) C1-4 thioalkoxy, or
s) cyano.
In a sub-subfamily of the subfamily of compounds, R2 is pyridyl, methoxypyridyl, or phenyl.
Examples of the family are listed below (note that methyl substituents are conventionally indicated as bonds attached to an atom). Inhibitory activity of compounds of the invention is represented by xe2x80x9c**xe2x80x9d, indicating Ki greater than or equal to 1 nM, or xe2x80x9c*xe2x80x9d, indicating Ki less than 1 nM. Values are as determined according to the in vitro assay described later in the specification. 
The compounds of the present invention, may have chiral centers and occur as racemates, racemic mixtures and as individual diastereomers, or enantiomers with all isomeric forms being included in the present invention. The compounds of the present invention may also have polymorphic crystalline forms, with all polymorphic crystalline forms being included in the present invention.
The invention also includes metabolites of the compounds of the invention, including the following compounds: 
When any variable occurs more than one time in any constituent or in formula I, its definition on each occurrence is independent of its definition at every other occurrence. Also, combinations of substituents and/or variables are permissible only if such combinations result in stable compounds.
Some abbreviations that may appear in this application are as follows.
As used herein except where noted, xe2x80x9calkylxe2x80x9d is intended to include both branched- and straight-chain saturated aliphatic hydrocarbon groups having the specified number of carbon atoms. Commonly used abbreviations for alkyl groups are used throughout the specification, e.g. methyl may be represented by xe2x80x9cMexe2x80x9d or CH3, ethyl may be represented by xe2x80x9cEtxe2x80x9d or CH2CH3, propyl may be represented by xe2x80x9cPrxe2x80x9d or CH2CH2CH3, butyl may be represented by xe2x80x9cBuxe2x80x9d or CH2CH2CH2CH3, etc.; xe2x80x9calkoxyxe2x80x9d represents a linear or branched alkyl group of indicated number of carbon atoms attached through an oxygen bridge; xe2x80x9cHaloxe2x80x9d, or xe2x80x9chalogenxe2x80x9d, as used herein, means fluoro (F), chloro (Cl), bromo (Br) and iodo (I); and xe2x80x9ccounterionxe2x80x9d is used to represent a small, single negatively-charged species, such as chloride, bromide, hydroxide, acetate, trifluoroacetate, perchlorate, nitrate, benzoate, maleate, sulfate, tartrate, hemitartrate, benzene sulfonate, and the like.
The term xe2x80x9cC3-7cycloalkylxe2x80x9d is intended to include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl, and the like.
The term xe2x80x9cC7-12 bicyclic alkylxe2x80x9d is intended to include bicyclo[2.2.1]heptyl (norbornyl), bicyclo[2.2.2]octyl, 1,1,3-trimethylbicyclo[2.2.1]heptyl (bornyl), and the like.
The term xe2x80x9carylxe2x80x9d as used herein except where noted, represents a stable 6- to 10-membered mono- or bicyclic ring system such as phenyl, or naphthyl. The aryl ring can be unsubstituted or substituted with one or more of C1-4 lower alkyl, hydroxy, alkoxy, halogen or amino.
The term xe2x80x9calkylarylxe2x80x9d, e.g., C1-3 alkylaryl, represents an aryl group having an alkyl substituent.
The term xe2x80x9cbiphenylxe2x80x9d means a ring assembly of two benzene rings, e.g., 
The term xe2x80x9cheterocyclic ringxe2x80x9d, as used herein except where noted, represents a stable 5- to 7-membered monocyclic- or stable 9- to 10-membered fused bicyclic heterocyclic ring system any ring of which may be saturated, such as piperidinyl, partially saturated, or unsaturated, such as pyridinyl, and which consists of carbon atoms and from one to four heteroatoms selected from the group consisting of N, O and S, and wherein the nitrogen and sulfur heteroatoms may optionally be oxidized, and the nitrogen heteroatom may optionally be quaternized, and including any bicyclic group in which any of the above-defined heterocyclic rings is fused to a benzene ring. Bicyclic unsaturated ring systems include bicyclic ring systems which may be partially unsaturated or fully unsaturated. Partially unsaturated bicyclic ring systems include, for example, cyclopentenopyridinyl, benzodioxan, methylenedioxyphenyl groups. Especially useful are rings containing one oxygen or sulfur, one to four nitrogen atoms, or one oxygen or sulfur combined with one or two nitrogen atoms. The heterocyclic ring may be attached at any heteroatom or carbon atom which results in the creation of a stable structure. Examples of such heterocyclic groups include piperidinyl, piperazinyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolodinyl, 2-oxoazepinyl, azepinyl, pyrrolyl, 4-piperidonyl, pyrrolidinyl, pyrazolyl, pyrazolidinyl, imidazolyl, imidazolinyl, imidazolidinyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, oxazolyl, oxazolidinyl, isoxazolyl, isoxazolidinyl, morpholinyl, thiazolyl, thiazolidinyl, isothiazolyl, quinuclidinyl, isothiazolidinyl, indolyl, quinolinyl, isoquinolinyl, benzimidazolyl, thiadiazoyl, benzopyranyl, benzothiazolyl, benzoxazolyl, furyl, tetrahydrofuryl, tetrahydropyranyl, tetrazole, thienyl, benzothienyl, thiamorpholinyl, thiamorpholinyl sulfoxide, thiamorpholinyl sulfone, and oxadiazolyl. Morpholino is the same as morpholinyl.
The term xe2x80x9cnon-heterocyclic ringxe2x80x9d, as used herein, except where noted, represents a stable 5- to 7-membered monocyclic, or stable 9- to 10-membered bicyclic ring system having carbon ring atoms and zero hetero ring atoms, which may be saturated, such cyclohexyl, partially saturated, or unsaturated, such as phenyl. Examples of such non-heterocyclic rings include phenyl, naphthylenyl, indenyl and cyclohexyl.
xe2x80x9cInhibitor of cyclooxygenase-2xe2x80x9d, xe2x80x9ccyclooxygenase-2 inhibitorxe2x80x9d and xe2x80x9cCOX-2 inhibitorxe2x80x9d as used herein embrace compounds which selectively inhibit cyclooxygenase-2 over cyclooxygenase-1.
The pharmaceutically-acceptable salts of the compounds of Formula I (in the form of water- or oil-soluble or dispersible products) include the conventional non-toxic salts such as those derived from inorganic acids, e.g. hydrochloric, hydrobromoic, sulfuric, sulfamic, phosphoric, nitric and the like, or the quaternary ammonium salts which are formed, e.g., from inorganic or organic acids or bases. Examples of acid addition salts include acetate, adipate, alginate, aspartate, benzoate, benzenesulfonate, bisulfate, butyrate, citrate, camphorate, camphorsulfonate, cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate, fumarate, glucoheptanoate, glycerophosphate, hemisulfate, heptanoate, hexanoate, hydrochloride, hydrobromide, hydroiodide, 2-hydroxyethanesulfonate, lactate, maleate, methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oxalate, pamoate, pectinate, persulfate, 3-phenylpropionate, picrate, pivalate, propionate, succinate, sulfate, tartrate, thiocyanate, tosylate, and undecanoate. Base salts include ammonium salts, alkali metal salts such as sodium and potassium salts, alkaline earth metal salts such as calcium and magnesium salts, salts with organic bases such as dicyclohexylamine salts, N-methyl-D-glucamine, and salts with amino acids such as arginine, lysine, and so forth. Also, the basic nitrogen-containing groups may be quaternized with such agents as lower alkyl halides, such as methyl, ethyl, propyl, and butyl chloride, bromides and iodides; dialkyl sulfates like dimethyl, diethyl, dibutyl; and diamyl sulfates, long chain halides such as decyl, lauryl, myristyl and stearyl chlorides, bromides and iodides, aralkyl halides like benzyl and phenethyl bromides and others.
In compounds of the invention having pyridyl N-oxide moieties, the pyridyl-N-oxide portion is structurally depicted using conventional representations such as 
which have equivalent meanings.
In the definition of variable xe2x80x9cAxe2x80x9d, when variable xe2x80x9cbxe2x80x9d is zero, A is 
When variable xe2x80x9cbxe2x80x9d is 1, A is 
Thrombin Inhibitorsxe2x80x94Therapeutic Usesxe2x80x94Method of Using
Anticoagulant therapy is indicated for the treatment and prevention of a variety of thrombotic conditions, particularly coronary artery and cerebrovascular disease. Those experienced in this field are readily aware of the circumstances requiring anticoagulant therapy. The term xe2x80x9cpatientxe2x80x9d used herein is taken to mean mammals such as primates, including humans, sheep, horses, cattle, pigs, dogs, cats, rats, and mice.
Thrombin inhibition is useful not only in the anticoagulant therapy of individuals having thrombotic conditions, but is useful whenever inhibition of blood coagulation is required such as to prevent coagulation of stored whole blood and to prevent coagulation in other biological samples for testing or storage. Thus, the thrombin inhibitors can be added to or contacted with any medium containing or suspected of containing thrombin and in which it is desired that blood coagulation be inhibited, e.g., when contacting the mammal""s blood with material selected from the group consisting of vascular grafts, stents, orthopedic prosthesis, cardiac prosthesis, and extracorporeal circulation systems.
Compounds of the invention are useful for treating or preventing venous thromboembolism (e.g. obstruction or occlusion of a vein by a detached thrombus; obstruction or occlusion of a lung artery by a detached thrombus), cardiogenic thromboembolism (e.g. obstruction or occlusion of the heart by a detached thrombus), arterial thrombosis (e.g. formation of a thrombus within an artery that may cause infarction of tissue supplied by the artery), atherosclerosis (e.g. arteriosclerosis characterized by irregularly distributed lipid deposits) in mammals, and for lowering the propensity of devices that come into contact with blood to clot blood.
Examples of venous thromboembolism which may be treated or prevented with compounds of the invention include obstruction of a vein, obstruction of a lung artery (pulmonary embolism), deep vein thrombosis, thrombosis associated with cancer and cancer chemotherapy, thrombosis inherited with thrombophilic diseases such as Protein C deficiency, Protein S deficiency, antithrombin III deficiency, and Factor V Leiden, and thrombosis resulting from acquired thrombophilic disorders such as systemic lupus erythematosus (inflammatory connective tissue disease). Also with regard to venous thromboembolism, compounds of the invention are useful for maintaining patency of indwelling catheters.
Examples of cardiogenic thromboembolism which may be treated or prevented with compounds of the invention include thromboembolic stroke (detached thrombus causing neurological affliction related to impaired cerebral blood supply), cardiogenic thromboembolism associated with atrial fibrillation (rapid, irregular twitching of upper heart chamber muscular fibrils), cardiogenic thromboembolism associated with prosthetic heart valves such as mechanical heart valves, and cardiogenic thromboembolism associated with heart disease.
Examples of arterial thrombosis include unstable angina (severe constrictive pain in chest of coronary origin), myocardial infarction (heart muscle cell death resulting from insufficient blood supply), ischemic heart disease (local anemia due to obstruction (such as by arterial narrowing) of blood supply), reocclusion during or after percutaneous transluminal coronary angioplasty, restenosis after percutaneous transluminal coronary angioplasty, occlusion of coronary artery bypass grafts, and occlusive cerebrovascular disease. Also with regard to arterial thrombosis, compounds of the invention are useful for maintaining patency in arteriovenous cannulas.
Examples of atherosclerosis include arteriosclerosis.
Examples of devices that come into contact with blood include vascular grafts, stents, orthopedic prosthesis, cardiac prosthesis, and extracorporeal circulation systems
The thrombin inhibitors of the invention can be administered in such oral forms as tablets, capsules (each of which includes sustained release or timed release formulations), pills, powders, granules, elixers, tinctures, suspensions, syrups, and emulsions. Likewise, they may be administered in intravenous (bolus or infusion), intraperitoneal, subcutaneous, or intramuscular form, all using forms well known to those of ordinary skill in the pharmaceutical arts. An effective but non-toxic amount of the compound desired can be employed as an anti-aggregation agent. For treating ocular build up of fibrin, the compounds may be administered intraocularly or topically as well as orally or parenterally.
The thrombin inhibitors can be administered in the form of a depot injection or implant preparation which may be formulated in such a manner as to permit a sustained release of the active ingredient. The active ingredient can be compressed into pellets or small cylinders and implanted subcutaneously or intramuscularly as depot injections or implants. Implants may employ inert materials such as biodegradable polymers or synthetic silicones, for example, Silastic, silicone rubber or other polymers manufactured by the Dow-Coming Corporation.
The thrombin inhibitors can also be administered in the form of liposome delivery systems, such as small unilamellar vesicles, large unilamellar vesicles and multilamellar vesicles. Liposomes can be formed from a variety of phospholipids, such as cholesterol, stearylamine or phosphatidylcholines.
The thrombin inhibitors may also be delivered by the use of monoclonal antibodies as individual carriers to which the compound molecules are coupled. The thrombin inhibitors may also be coupled with soluble polymers as targetable drug carriers. Such polymers can include polyvinlypyrrolidone, pyran copolymer, polyhydroxy-propyl-methacrylamide-phenol, polyhydroxyethyl-aspartamide-phenol, or polyethyleneoxide-polylysine substituted with palmitoyl residues. Furthermore, the thrombin inhibitors may be coupled to a class of biodegradable polymers useful in achieving controlled release of a drug, for example, polylactic acid, polyglycolic acid, copolymers of polylactic and polyglycolic acid, polyepsilon caprolactone, polyhydroxy butyric acid, polyorthoesters, polyacetals, polydihydropyrans, polycyanoacrylates and cross linked or amphipathic block copolymers of hydrogels.
The dosage regimen utilizing the thrombin inhibitors is selected in accordance with a variety of factors including type, species, age, weight, sex and medical condition of the patient; the severity of the condition to be treated; the route of administration; the renal and hepatic function of the patient; and the particular compound or salt thereof employed. An ordinarily skilled physician or veterinarian can readily determine and prescribe the effective amount of the drug required to prevent, counter, or arrest the progress of the condition.
Oral dosages of the thrombin inhibitors, when used for the indicated effects, will range between about 0.01 mg per kg of body weight per day (mg/kg/day) to about 30 mg/kg/day, preferably 0.025 mg/kg/day to 7.5 mg/kg/day, more preferably 0.1 mg/kg/day to 2.5 mg/kg/day, and most preferably 0.1 mg/kg/day to 0.5 mg/kg/day (unless specificed otherwise, amounts of active ingredients are on free base basis). For example, an 80 kg patient would receive between about 0.8 mg/day and 2.4 g/day, preferably 2 mg/day to 600 mg/day, more preferably 8 mg/day to 200 mg/day, and most preferably 8 mg/day to 40 mg/kg/day. A suitably prepared medicament for once a day administration would thus contain between 0.8 mg and 2.4 g, preferably between 2 mg and 600 mg, more preferably between 8 mg and 200 mg, and most preferably 8 mg and 40 mg, e.g., 8 mg, 10 mg, 20 mg and 40 mg. Advantageously, the thrombin inhibitors may be administered in divided doses of two, three, or four times daily. For administration twice a day, a suitably prepared medicament would contain between 0.4 mg and 1.2 g, preferably between 1 mg and 300 mg, more preferably between 4 mg and 100 mg, and most preferably 4 mg and 20 mg, e.g., 4 mg, 5 mg, 10 mg and 20 mg.
Intravenously, the patient would receive the active ingredient in quantities sufficient to deliver between 0.025-7.5 mg/kg/day, preferably 0.1-2.5 mg/kg/day, and more preferably 0.1-0.5 mg/kg/day. Such quantities may be administered in a number of suitable ways, e.g. large volumes of low concentrations of active ingredient during one extended period of time or several times a day, low volumes of high concentrations of active ingredient during a short period of time, e.g. once a day. Typically, a conventional intravenous formulation may be prepared which contains a concentration of active ingredient of between about 0.01-1.0 mg/ml, e.g. 0.1 mg/ml, 0.3 mg/ml, and 0.6 mg/ml, and administered in amounts per day of between 0.01 ml/kg patient weight and 10.0 ml/kg patient weight, e.g. 0.1 ml/kg, 0.2 ml/kg, 0.5 ml/kg. In one example, an 80 kg patient, receiving 8 ml twice a day of an intravenous formulation having a concentration of active ingredient of 0.5 mg/ml, receives 8 mg of active ingredient per day. Glucuronic acid, L-lactic acid, acetic acid, citric acid or any pharmaceutically acceptable acid/conjugate base with reasonable buffering capacity in the pH range acceptable for intravenous administration may be used as buffers. Consideration should be given to the solubility of the drug in choosing an The choice of appropriate buffer and pH of a formulation, depending on solubility of the drug to be administered, is readily made by a person having ordinary skill in the art.
The compounds can also be administered in intranasal form via topical use of suitable intranasal vehicles, or via transdermal routes, using those forms of transdermal skin patches well known to those of ordinary skill in that art. To be administered in the form of a transdermal delivery system, the dosage administration will, or course, be continuous rather than intermittent throughout the dosage regime.
The thrombin inhibitors are typically administered as active ingredients in admixture with suitable pharmaceutical diluents, excipients or carriers (collectively referred to herein as xe2x80x9ccarrierxe2x80x9d materials) suitably selected with respect to the intended form of administration, that is, oral tablets, capsules, elixers, syrups and the like, and consistent with convention pharmaceutical practices.
For instance, for oral administration in the form of a tablet or capsule, the active drug component can be combined with an oral, non-toxic, pharmaceutically acceptable, inert carrier such as lactose, starch, sucrose, glucose, methyl cellulose, magnesium stearate, dicalcium phosphate, calcium sulfate, mannitol, sorbitol and the like; for oral administration in liquid form, the oral drug components can be combined with any oral, non-toxic, pharmaceutically acceptable inert carrier such as ethanol, glycerol, water and the like. Moreover, when desired or necessary, suitable binders, lubricants, distintegrating agents and coloring agents can also be incorporated into the mixture. Suitable binders include starch, gelatin, natural sugars such as glucose or beta-lactose, corn-sweeteners, natural and synthetic gums such as acacia, tragacanth or sodium alginate, carboxymethylcellulose, polyethylene glycol, waxes and the like. Lubricants used in these dosage forms include sodium oleate, sodium stearate, magnesium stearate, sodium benzoate, sodium acetate, sodium chloride and the like. Disintegrators include, without limitation, starch methyl cellulose, agar, bentonite, xanthan gum and the like.
The invention also includes a method for treating an inflammatory disease in a patient which comprises treating the patient with a composition comprising a compound of the present invention. Such diseases include but are not limited to nephritis, systemic lupus erythematosus, rheumatoid arthritis, glomerulonephritis, and sacoidosis.
The invention is also a method for treating an inflammatory disease in a patient that comprises treating the patient with a combination comprising a compound of the invention and an NSAID, e.g., a COX-2 inhibitor. Such diseases include but are not limited to nephritis, systemic lupus, erythematosus, rheumatoid arthritis, glomerulonephritis, vasculitis and sacoidosis.
The present invention is a method for relieving pain, fever and inflammation of a variety of conditions including nephritis, systemic lupus erythematosus, rheumatoid arthritis, glomerulonephritis, sacoidosis, rheumatic fever, symptoms associated with influenza or other viral infections, common cold, low back and neck pain, dysmenorrhea, headache, toothache, sprains and strains, myositis, neuralgia, synovitis, arthritis, including rheumatoid arthritis degenerative joint diseases (osteoarthritis), gout and ankylosing spondylitis, bursitis, burns, injuries, following surgical and dental procedures in a patient by administering to the patient a therapeutically effective amount of a compound of the invention. Thrombin inhibitors may also be useful for the treatment of dementia including pre-senile and senile dementia, and in particular, dementia associated with Alzheimer Disease.
In inflammatory diseases wherein fibrin formation is prominent, the fibrin may be a determinant of the pathology. Fibrin serves as a matrix onto which inflammatory cells can migrate and adhere. (see Sherman et al., 1977 J. Exp. Med. 145:76-85; Altieri et al., 1986 J. Clin. Invest. 78:968-976; Wright et al., 1983 Proc. Natl. Acad. Sci. 85:7734-7738; Altieri et al., 1993 J. Biol. Chem. 268;1847-1853). Fibrin also enhances expression of the inflammatory cytokine IL-1beta and decreases expression of IL-1 receptor antagonist by human peripheral blood mononuclear cells (see Perez 1995 J. Immunol. 154:1879-1887). The anticoagulants warfarin and heparin attenuate delayed-type hypersensitivity reactions and experimental nephritis in animals. (see Jasain et al., Immunopathogenesis of Rheumatoid Arthritis Eds. G. S. Panayi et al., Surrey, UK, Reedbooks, Ltd. and Halpern et al., 1965 Nature 205:257-259). Enzymatic defibrination with ancrod diminishes the degree of experimental nephritis (Naish et al., 1972 Clin. Sci. 42:643-646), systemic lupus erythematosus (Cole et al., 1990 Kidney Int. 37:29-35, and rheumatoid arthritis (see Busso et al., 1998 J. Clin. Invest. 102:41-50) in animals, and glomerulonephritis in man (see Kim et al., 1988 Q. J. Med. 69:879-905). Additionally, intra articular injection of fibrin induces arthritis in rabbits immunized with fibrin Dumonde et al., 1961 British Journal of Experimental Pathology XLIII:373-383), and antigen-induced arthritis in mice is exacerbated in urokinase-deficient mice wherein fibrinolysis synovial fibrin is compromised (see Busso et al., 1998 J. Clin. Invest. 102:41-50).
In diseases where fibrin deposition is prominent such as, but not limited to, rheumatoid arthritis, systemic lupus erythematosus, glomerulonephritis, vasculitis and sacoidosis, lowering the steady state concentration of fibrin by administration of a compound of the invention will, according to the instant invention, diminish the pathological inflammatory responses associated with these diseases.
Similarly, compounds of the invention will be useful as a partial or complete substitute for conventional NSAIDs in preparations wherein they are presently co-administered with other agents or ingredients. Thus in further aspects, the invention encompasses pharmaceutical compositions for treating inflammatory diseases as defined above comprising a non-toxic therapeutically effective amount of a compound of the invention as defined above and one or more ingredients such as another pain reliever including acetominophen or phenacetin; a potentiator including caffeine; an H2-antagonist, aluminum or magnesium hydroxide, simethicone, a decongestant including phenylephrine, phenylpropanolamine, pseudophedrine, oxymetazoline, ephinephrine, naphazoline, xylometazoline, propylhexedrine, or levodesoxyephedrine; an antiitussive including codeine, hydrocodone, caramiphen, carbetapentane, or dextramethorphan; a diuretic; a sedating or non-sedating antihistamine. In addition the invention encompasses a method of treating inflammatory diseases comprising administration to a patient in need of such treatment a non-toxic therapeutically effect amount of a compound of the invention, optionally co-administered with one or more of such ingredients as listed immediately above.
The instant invention also involves a novel combination therapy comprising the administration of a therapeutically effective amount of an NSAID such as a COX-2 inhibitor in combination with a therapeutically effective amount of a compound of the invention to a mammal, and more particularly, to a human. The combination therapy is used to treat inflammatory diseases.
The instant pharmaceutical combinations comprising a compound of the invention in combination with an NSAID such as a COX-2 inhibitor include administration of a single pharmaceutical dosage formulation which contains both a compound of the invention and the NSAID, as well as administration of each active agent in its own separate pharmaceutical dosage formulation. Where separate dosage formulations are used, the compund of the invention and the NSAID can be administered at essentially the same time, i.e., concurrently, or at separately staggered times, i.e, sequentially. The xe2x80x9cinstant pharmaceutical combinationxe2x80x9d is understood to include all these regimens. Administration in these various ways are suitable for the present invention as long as the beneficial pharmaceutical effect of the compound of the invention and the NSAID are realized by the patient at substantially the same time. Such beneficial effect is preferably achieved when the target blood level concentrations of each active drug are maintained at substantially the same time. It is preferred that the compound of the invention and the NSAID be co-administered concurrently on a once-a-day dosing schedule; however, varying dosing schedules, such as the compound of the invention once per day and the NSAID once, twice or more times per day, or the NSAID once per day and the compound of the invention once, twice or more times per day, is also encompassed herein. A single oral dosage formulation comprised of both the compound of the invention and the NSAID is preferred. A single dosage formulation will provide convenience for the patient.
The instant invention also provides pharmaceutical compositions comprised of a therapeutically effective amount of an NSAID, or a pharmaceutically acceptable salt thereof, in combination with a therapeutically effective amount of a compound of the invention, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier. One embodiment of the instant compositions is a single composition adapted for oral administration comprised of a therapeutically effective amount of a COX-2 inhibitor in combination with a therapeutically effective amount of a compound of the invention and a pharmaceutically acceptable carrier. The combination can also be administered in separate dosage forms, each having one of the active agents. If administered in separate dosage forms, the separate dosage forms are administered such that the beneficial effect of each active agent is realized by the patient at substantially the same time.
Common NSAIDs include salicylates such as aspirin, sodium salicylate, choline salicylate, salicylsalicylic acid, diflunisal, and salsalate; indoleacetic acids such as indomethacin and sulindac; pyrazoles such as phenylbutazone, oxyphenbutazone; pyrrolealkanoic acids such as tolmetin; phenylacetic acids such as ibuprofen, feroprofen, flurbiprofen, and ketoprofen; fenamates such as mefanamic acid, and meclofenamate; oxicams such as piroxicam; and naphthaleneacetic acids such as naproxen. Cyclo-oxygenase inhibitors such as COX-1 and COX-2 inhibitors are also NSAIDs.
Employing the human whole blood COX-1 assay and the human whole blood COX-2 assay described in C. Brideau et al, Inflamm. Res. 45: 68-74 (1996), herein incorporated by reference, preferably, the compounds have a cyclooxygenase-2 IC50 of less than about 2 xcexcM in the human whole blood COX-2 assay, yet have a cyclooxygenase-1 IC50 of greater than about 5 xcexcM in the human whole blood COX-1 assay. Also preferably, the compounds have a selectivity ratio of cyclooxygenase-2 inhibition over cyclooxygenase-1 inhibition of at least 10, and more preferably of at least 40. The resulting selectivity may indicate an ability to reduce the incidence of common NSAID-induced side effects.
The inhibitor of cyclooxygenase-2 may be administered at a dosage level up to conventional dosage levels for NSAIDs. Suitable dosage levels will depend upon the antiinflammatory effect of the chosen inhibitor of cyclooxygenase-2, but typically suitable levels will be about 0.001 to 50 mg/kg per day, preferably 0.005 to 30 mg/kg per day, and especially 0.05 to 10 mg/kg per day. The compound may be administered on a regimen of up to 6 times per day, preferably 1 to 4 times per day, and especially once per day.
The dosage regimen utilizing a compound of the invention in combination with the NSAID is selected in accordance with a variety of factors including type, species, age, weight, sex and medical condition of the patient; the severity of the condition to be treated; the route of administration; the renal and hepatic function of the patient; and the particular compound or salt or ester thereof employed. Since two different active agents are being used together in a combination therapy, the potency of each of the agents and the interactive effects achieved by combining them together must also be taken into account. A consideration of these factors is well within the purview of the ordinarily skilled clinician for the purpose of determining the therapeutically effective or prophylactically effective dosage amounts needed to prevent, counter, or arrest the progress of the condition.
Administration of the drug combination to the patient includes both self-administration and administration to the patient by another person.
Additional active agents may be used in combination with the compound of the invention in a single dosage formulation, or may be administered to the patient in a separate dosage formulation, which allows for concurrent or sequential administration. Examples of additional active agents which may be employed include HMG-CoA synthase inhibitors; squalene epoxidase inhibitors; squalene synthetase inhibitors (also known as squalene synthase inhibitors), acyl-coenzyme A: cholesterol acyltransferase (ACAT) inhibitors; probucol; niacin; fibrates such as clofibrate, fenofibrate, and gemfibrizol; cholesterol absorption inhibitors; bile acid sequestrants; LDL (low density lipoprotein) receptor inducers; vitamin B6 (also known as pyridoxine) and the pharmaceutically acceptable salts thereof such as the HCl salt; vitamin B12 (also known as cyanocobalamin); xcex2-adrenergic receptor blockers; folic acid or a pharmaceutically acceptable salt or ester thereof such as the sodium salt and the methylglucamine salt; and anti-oxidant vitamins such as vitamin C and E and beta carotene.
The thrombin inhibitors can also be co-administered with suitable anti-platelet agents, including, but not limited to, fibrinogen receptor antagonists (e.g. to treat or prevent unstable angina or to prevent reocclusion after angioplasty and restenosis), anticoagulants such as aspirin, thrombolytic agents such as plasminogen activators or streptokinase to achieve synergistic effects in the treatment of various vascular pathologies, or lipid lowering agents including antihypercholesterolemics (e.g. HMG CoA reductase inhibitors such as lovastatin and simvastatin, HMG CoA synthase inhibitors, etc.) to treat or prevent atherosclerosis. For example, patients suffering from coronary artery disease, and patients subjected to angioplasty procedures, would benefit from coadministration of fibrinogen receptor antagonists and thrombin inhibitors. Also, thrombin inhibitors enhance the efficiency of tissue plasminogen activator-mediated thrombolytic reperfusion. Thrombin inhibitors may be administered first following thrombus formation, and tissue plasminogen activator or other plasminogen activator is administered thereafter.
Typical doses of thrombin inhibitors of the invention in combination with other suitable anti-platelet agents, anticoagulation agents, or thrombolytic agents may be the same as those doses of thrombin inhibitors administered without coadministration of additional anti-platelet agents, anticoagulation agents, or thrombolytic agents, or may be substantially less that those doses of thrombin inhibitors administered without coadministration of additional anti-platelet agents, anticoagulation agents, or thrombolytic agents, depending on a patient""s therapeutic needs.
Compounds having the general structure 
wherein W, X and R3 have the above-described meanings and A is fluoropyridyl, can be prepared by reacting 
with 
under conditions suitable for forming amide bond between the acid and the amine.
Suitable carboxylic acid starting materials for 
may be prepared according to the following procedures described in Sanderson et al., WO 97/40024, specifically Method 1 through step F and corresponding Example I, Method 2 and corresponding Example III, Method 3 through step E and corresponding Example V, and Method 5 through step E and corresponding Example LXXXII, on pages 29-58 and 108-111, the contents of which are hereby incorporated by reference. Alternatively, they may be prepared using ethyl 3-bromo-6-methylpyrazin-2-one-1-acetate (see Sanderson et al., WO 99/11267, compound 7-4, pages 34-37 the contents of which are hereby incorporated by reference, referenced as compound xe2x80x9cAxe2x80x9d) in a condensation reaction with Wxe2x80x94NH2, followed by saponification which leads to the corresponding acid.
Compounds are then formed by reacting the carboxylic acid with 
as shown below: 
wherein 
can be, for example, 2-aminomethyl-3-fluoropyridine (referenced as compound xe2x80x9cBxe2x80x9d) and related fluoropyridine derivatives, in order to form the finished product. 2-aminomethyl-3-fluoropyridine is prepared as follows: 
Synthesis of 2-aminomethyl-3-fluoropyridine begins with catalytic reduction of 2-cyano-3-fluoropyridine (Sakamoto et al., Chem. Pharm. Bull. 33(2) 565-571 (1985)) using palladium on carbon which provides 2-aminomethyl-3-fluoropyridine B as the dihydrochloride salt.
The coupling of 2-aminomethyl-3-fluoropyridine B and 3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-methylpyrazin-2-one-1-acetic acid is carried out in DMF using EDC, HOBT and triethylamine. Addition of water precipitates the product which is then purified by silica gel chromatography to give the title compound as a slightly colored solid. Conversion to its hydrochloride salt can be carried out by treating an ethyl acetate solution with two equivalents of 1M HCl in ethyl acetate, followed by filtration.
2-Aminomethyl-3-fluoropyridine (B) as a Dihydrochloride Salt
A stirred solution of 6.11 g (50.1 mmol) of 2-cyano-3-fluoropyridine in 250 mL of ethanol and 12.5 mL (150 mmol) of conc. HCl was hydrogenated over 1.90 g of 10% palladium on carbon at 40 psi for 16 h. The catalyst was removed by filtration and the solvents removed at reduced pressure. The resulting solid was diluted with acetonitrile and filtered to give 8.0 g of the title compound as an off-white solid: 1H NMR (CD3OD) xcex4 8.48 (d, 1H, 4.8 Hz), 7.69 (td, 1H, 9.2, 1.1 Hz), 7.68 (ddd, 1H, 8.8, 4.4, 4.4 Hz), 4.34 (s, 2 H).
Typically, solution phase amide couplings may be used to form the final product, but solid-phase synthesis by classical Merrifield techniques may be employed instead. The addition and removal of one or more protecting groups is also typical practice.
Compounds having different groups at variable A can be prepared by coupling alternative commercially available amino derivatives 
where Y1 and Y2 are defined above, using the coupling procedure described for coupling 
to the carboxylic acid. Alternative amino derivatives and methods for preparing amino derivatives are known to those skilled in the art and described below.
1) 
is commercially available.
2) 
and also for example 
Unless otherwise stated, all NMR determinations were made using 400 MHz field strength.